Mining-machine bit



July 24, 1923. 1,462,681 I N. K. BOWMAN MINING MACHINE BIT Filed Dec. 151921 Patented Jelly 24-, 11923.

UNHTED STATES NEWTQN BOWMAN, OFBOWDTL, DEE 0.

MINING-MACHINE BIT.

application filed December 15, 1921. Serial No. 522,57t.

To all whom it may concern:

Be it brown that l, Nnwro-N K. BOWMAN, a citizen of the United States,residing at Bowdil, in the county of Stark and State of @hio, haveinvented certain new and usetul improvements in Mining-Machine Bits, ofwhich the following is a specification.

This invention relates to detachable bits for mining machines and hasfor its object the provision of means whereby the bit will he firmlyheld and also to provide a con struction which will offer ampleclearance for the dust present during operation of the mining machine. Afurther object of the invention is to provide a construction wherehy thebit will be firmly seated in the cutter har or shank and may be readilyremoved and reversed when necessary or desirable. These several statedobjects and other objects which will incidentally appear in the courseof the following description are attained in such a construction as isillustrated in the accompanying drawings, and the invention consists incertain novel features which will be particularly pointed out in theclaims following the description.

Tn the drawings I Fig. l is a perspective view of my improved hitapplied to a cutter bar or shank of a mining machine;

Fig. 2 is a longitudinal section through the bit and the partscooperating therewith;

"Fig. 3 is a transverse section on the line 33 of Fig. 2;

Fig. 4 is a detail side elevation of the bit;

Fig. 5 is a detail section of the holder or clamp taken on the line 5--5of Fig. 1.

lln the drawings, the reference numeral 1 indicates a cutter her orshank which forms a part of an endless chain of cutters which aregenerally employed in coal-mining machines. In the present instance, thetree or working end of the cutter bar or shank ismade convex andinclines from the front edge to the back edge of the bar, as shown at 2.Excessive contact hetween the 'end of the her and the wall of the mineis thus avoided and clearance for dust hack of the bit is provided.Disposed longitudinally in the front edge of the loar is a seat 3 whichis concave at its back wall and the side walls of which converge fromthe upper and lower sides of the cutter bar, as shown most clearly at 4in Fig. 3. The seat 3 extends. through th c'extremity of the cutter bar,as shown at 5, where a substantially and has a convex longitudinal ridge8 which, as clearly shown in the drawings, is caused to follow an arc ofthe same radius as the back'wall or apex of the longitudinal seat 3. Thehit is hollow, as indicated at 9, although its walls are of sufficientthickness to possess the strength necessary to overcome the resistanceofiered by the vein of coal to its operation, and the edges of the sidewalls of the hit are so formed as to present concavities 10 at each endwhich follow arcs W of shorter radii than the are back ridge 8 of thebit. By reference to Fig. 41, it will be readily noted that the linesupon which the front and back edges of the hit are formed present asharp point ii at each end thereof and this point 11 constitutes theprimary cutting agent. The edges 10 are also sharpened so that the hitwill readily out into and break oh the coal in clean lumps ofappreciable size and, in actual practice, the hack of the bit is ofrelatively soft metal while the cutting edges are hardened. The activepoint of the hit projects beyond the extremity of the cutter har orshank and there is, consequently, ample clearance hack of the hit forthe talling chips and dust, while the peculiar formation of the hit willpermit it to rest firmly in the seat 3 so that the thrust upon thecutting faces or points or edges will he transmitted to the cutter bar.llnasmuch as the back of the bit is of relatively soft metal, the slightwear which may occur between the hit and its seat will serve to fit theopposed surfaces to each other so that after the hit has heen used for atime it will possibly engage its seat more firmly and evenly than whenfirst produced. The peculiar shape or the working "faces of the hit, aswell as the defined hy the hardening of the same. will cause the hit Ito he self-sharpening so that it will need no attention for a longperiod. Between the concave arcuate portions of its edges 10, notches 12are provided in the edges of the hit. thereby producing shoulders 13suhstantiallv transverse to the respective edges. To retain the bit inits seat, I provide a holder as will be presently set i ice or clamp 14which is in the form of a 1008 or stirrup adapted to fit over the hit anthe end of the cutter bar and is equipped with a set screw 15 in itshead which is adapted to be turned home against the back edge of thecutter bar and thereby draw the front end of the loop into closeengagement with the bit and bind the bit to its seat. As shown mostclearly in Fig. 5, the outer faces 16 of the holder or clamp convergetoward the outer end of the cutter bar, this formation tending to reducethe liability of frictional wear upon the holder through contact betweenthe sides of the same and the vein of coal. The front end of the holderor clamp is provided with an internal rib 17 which is adapted to enterthe grooved or hollow portion 9 of the bit and, when the bit is inworking position, the outer shoulders 13 will abut the outer edge of theholder or clamp, as shown clearly in Figs. 1 and 2, so that the thrustwill be transmitted through the bit to the holder. In the opposite sidesof this rib or boss 17 1 provide cavities 18 which, as shown by dottedlines in Fig. 2, present shoulders to be en; gaged by the rear shoulders13 of thebit when the latter is in its working position, the portion ofthe rib intervening between the cavities 18 extending between thecorresponding shoulders 13 so thatwhen the set screw is turned home, thebit will be in interlocking engagement with the holder or clamp andmovement of the bit in either direction through the clamp will bepositively prevented. The shoulders 13 are obviously formed at thewidest part of the bit, the sides of the bit tapering in both directionstowards its end or extremities whereby the entering points are formed,as heretofore stated and as clearly shown in the drawings. The outerportions of these shoulders will, consequently, form the widest portionsof the bit, and the holder is so formed that the engagement of theshoulders with the holder will occur at the junction of its forward endwall and its upper and lower side walls respectively, the openingthrough the holder being, consequently. just sufficient to admit thecutter bar so that the portions of the holder engaged by the bit passthrough the notches 12 of the bit and through the cutaway portions 6 ofthe cutter bar. To permit the bit to be engaged in the holder, I provideon the inner faces of the top and bottom walls of the holders grooves 19which merge into the cavities 18, as shown most clearly in Fig. 5. Asthe extreme width of th bit is greater than the width of the openingthrough the holder, these grooves permit the bit to be readily engagedin the holder inasmuch as the bit may be inserted in the holder with itswidest portion disposed along the length of the holder, and if a quarterturn be then given the bit in either direction, the working side of thesam will be brought into proper enga ement with the rib 17 and the seats18, t e grooves 19 accommodating the width of the bit at the innershoulders 13 of the same. After the bit has been thus assembled with theholder, the holder and bit are easily assembled with the cutter bar bymerely inserting the end of the cutter bar through the holder and thenturning home the set screw. When the parts are thus assembled, the bitwill be held firmly and positively against movement in any direction andwill be enabled to effectually overcome the resistance thrust upon it bythe vein of coal. Obviously, when one end or point of the bit has beenworn to such an extent as to be no longer fit for practical use, the bitmay be removed from the holder and the cutter bar and then reversed sothat the formerly inactive point may be utilized.

Having thus described the invention, what is claimed as new is:

1. The combination of a cutter bar having :a longitudinally extendingconcave seat at its free end and provided with a notch at the end ofsaid seat forming a terminal of the seat, a bit having its sides iiaredand its back forming a longitudinally extending convex ridge adapted tofit in the said seat, the forward side of the bit being provided withconcave arcuate portions merging into the back of the bit to formcutting points, a holder fitting around the bit and the cutter bar, andmeans carried by the holder to engage the cutter bar and bind the bit inthe seat.

2. The combination of a cutter bar having a longitudinal seat in itsfront edge at its free end, a bit adapted to fit snugly in said seat andprovided centrally with spaced shoulders on its forward side, saidshoulders being disposed in advance of the sides of the seat, a holderadapted to encircle the end of the cutter bar and constructed to engagethe bit between the shoulders thereon and between the inner shoulder andthe inner end of the bit, and means for securing th holder rigidly uponthe cutter bar.

3. The combination of a cutter-bar having a longitudinal seat at itsfree end in its front edge, the front side of said seat being open, abit adapted to fit snugly in said seat and provided centrally withspaced trans.

verse shoulders on its front side, the said shoulders being in advanceof the sides of the seat, a clamp fitting around the free end of thecutter bar and provided internally with a cavity to receive onetransverse shoulder of the bit whereby the body of the clamp between itsouter edge and said cavi? may fit snugly between and interlock wi theshoulders on the bit, and means for securing the clamp firmly upon thecutter bar.

4, The combination with a cutter bar havgreener ing a longitudinal seatin its nt edge et its free end, of a symmetrical reversible bit adaptedto fit snugly within said seat with either end projecting through theend of the cutter bar and its opposite end housed in the seat, andprovided centrally with speced shoulders on its working side, the bittapering from said shoulders toward both its ends, a holder fittingaround the cutter bar at the free end of the same and having abit-engaging portion constructed to inter lock with the said shouldersand bind the housed end of the bit within the seat, and means forsecuring said holder upon the cutter her.

5. The combination of a cutter bar having a longitudinally extendingseat at its free end, a bit fitting snugly in said seat andheving itsside walls flaring outwardly at its center and converging toward itsends, notches formed in the edges of the bit at the center thereofwhereby to define spaced shoulders on the hit, a holder encircling theend of the cutter bar and the bit and hav ing a portion pessing throughthe notches in the bit and engaging the shoulders thereon, and means forsecuring said holder to the cutter her.

6. 'The combination of u cutter bar having a longitudinally extendingseat at its free end, a bit adapted to fit snuglyrin said sent andhaving its cutting edges tapering from its center toward! its ends,spaced shoulders being provided upon said edges midwey the ends thereof,a holder encircling the end of the cutter bar and provided on its innerside with a rib to fit longitudinelly of the hit between the cuttingedges of the same, the said rib heing provided in its opposite sideswith cavities to acooodate some of the shoulders on the bit whereby thehit and the holder will edect interloc engagement, and means forsecuring the holder rig dly upon the cutter bar.

The combination of a cutter bar hav a longitudinal seat at its free end,e, bit he ing its sides flaring outwardly from its back and convergingtoward its ends end pro-= vided with spewed shoulders on its front edgesmidway its ends, a holder encircli the cutter her and provided with onintended boss to fit between the es of the bit and cavities to receivethe shoulders on the bit whereby the holder may efit'ect interlockingengagement with the bit between the shoulders thereon, the holder beingprovided in opposite sides with oves leading into said wvities wherebyto permit turning of the hit in assembling the ports, and means forsecuring the holder rigidly upon the cutter bar.

8. A. bit for mining machines heving spaced wells, end in longtiudinellyconvex hack, the side walls diverging from the said convex back andconverging toward the ends thereof, the edges or the wall being providedwith notches at the centers thereof whereby to define spnced shouldersand being arouate between the seid shoulders and the ends or the heel;whereby to form concave cu tin edges.

n testimony whereof I afin rny signeture.

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